In conventional fuel delivery systems for internal combustion engines, a constant-delivery fuel pump supplies fuel under pressure from a tank to a fuel rail positioned on the engine. A plurality of fuel injectors are mounted between the fuel rail and the engine intake manifold, with the injector nozzles being positioned adjacent to the fuel/air intake ports of the individual engine cylinders. The fuel injectors are individually electromagnetically actuated by an engine control unit as a function of operating conditions and parameters at the engine.
A major cost associated with fuel delivery systems of the described character lies in the individual fuel injectors, and in the complexity of electrical conductors that connect the fuel injectors to the engine control unit. The fuel injectors are subject to wear, and may eventually feed differing quantities of fuel to the cylinders even when actuated for nominally identical time durations, thus resulting in less than optimum engine operation. Furthermore, conventional fuel injectors present additional difficulties when employed in conjunction with so-called alternative fuels. Fuels of this character have lower lubricity than conventional gasoline fuels, increasing wear at the individual injectors. The injector wear parts may be constructed of stainless steel, for example, which reduces wear but greatly increases cost. Moreover, because of lower energy content of alcohol-based alternative fuels, for example, the injectors must have a larger fuel opening and/or remain open longer than would otherwise be desirable in operation with gasoline. Thus, conventional fuel injectors are not well suited for use in association with engines intended for operation with alternative fuels having different potential energy contents.
U.S. Pat. No. 5,341,785 to Meaney discloses a fuel delivery system for internal combustion engines including a fuel-metering distributor. The Meaney system eliminates conventional electromagnetic fuel injectors, thereby achieving reduced cost, reduced complexity, reduced wear and increased operating life. The Meaney system also automatically delivers identical quantities of fuel to all of the engine cylinders, and automatically controls fuel quantity over a wide flow range with multiple fuel types without requiring adjustment by an operator or engine technician. The fuel-metering distributor disclosed in Meaney includes a fuel cavity and apertures in a sidewall of the fuel cavity coupled to associated individual fuel lines. A piston is slidingly disposed in the fuel cavity for opening the individual apertures as a function of position of the piston within the cavity, and a linear electromagnetic actuator is coupled to the piston for controlling the position of the piston within the cavity.
What is desired, however, is a fuel distributor wherein the fuel flow through each aperture, or fuel outlet, can be individually adjusted to optimize performance.